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CVE-2021-21328

5.3 · MEDIUM

Vapor is a web framework for Swift.

Published Feb 26, 2021CWE-400EPSS 1.84%

Overview

CVE-2021-21328 is a medium-severity vulnerability. It was published on February 26, 2021 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Vapor is a web framework for Swift. In Vapor before version 4.40.1, there is a DoS attack against anyone who Bootstraps a metrics backend for their Vapor app. The following is the attack vector: 1. send unlimited requests against a vapor instance with different paths. this will create unlimited counters and timers, which will eventually drain the system. 2. downstream services might suffer from this attack as well by being spammed with error paths. This has been patched in 4.40.1. The `DefaultResponder` will rewrite any undefined route paths for to `vapor_route_undefined` to avoid unlimited counters.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/vapor/vapor/commit/e3aa712508db2854ac0ab905696c65fd88fa7e23GitHubgithub.com/vapor/vapor/releases/tag/4.40.1GitHubgithub.com/vapor/vapor/security/advisories/GHSA-gcj9-jj38-hwmcRefvapor.codes/GitHubgithub.com/vapor/vapor/commit/e3aa712508db2854ac0ab905696c65fd88fa7e23GitHubgithub.com/vapor/vapor/releases/tag/4.40.1GitHubgithub.com/vapor/vapor/security/advisories/GHSA-gcj9-jj38-hwmcRefvapor.codes/

How CyberStrike helps

Frequently asked questions

What is CVE-2021-21328?

CVE-2021-21328 is a medium-severity vulnerability. It was published on February 26, 2021 and has a CVSS 3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2021-21328?

This vulnerability has a CVSS 3.1 base score of 5.3, rated MEDIUM. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-21328?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-21328?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-21328 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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